Numerous studies have demonstrated that both the risk of coronary heart disease (CHD) in humans and the severity of experimental atherosclerosis in animals are inversely correlated with serum HDL cholesterol (HDL-C) concentrations (Russ et al, Am. J. Mede, 11 (1951) 480-493; Gofman et al, Circulation, 34 (1966) 679-697; Miller and Miller, Lancet, 1 (1975) 16-19; Gordon et al, Circulation, 79 (1989) 8-15; Stampfer et al, N. Engl. J. Med., 325 (1991) 373-381; Badimon et al, Lab. Invest., 60 (1989) 455-461 ). Atherosclerosis is the process of accumulation of cholesterol within the arterial wall which results in the occlusion, or stenosis, of coronary and cerebral arterial vessels and subsequent myocardial infarction and stroke. Angiographical studies have shown that elevated levels of some HDL particles appears to be correlated with a decrease in the number of sites of stenosis in the coronary arteries of humans (Miller et al, Br. Med. J., 282 (1981) 1741-1744).
There are several mechanisms by which HDL may protect against the progression of atherosclerosis. Studies in vitro have shown that HDL is capable of removing cholesterol from cells (Picardo et al, Arteriosclerosis, 6 (1986) 434-441). Data of this nature suggests that one antiathero, genic property of HDL may lie in its ability to deplete tissues of excess free cholesterol and eventually lead to the delivery of this cholesterol to the liver (Glomset, J. Lipid Res., 9 (1968) 155-167). This has been supported by experiments showing efficient transfer of cholesterol from HDL to the liver (Glass et al, Circulation, 66 (Suppl. I) (1982) 102; MacKinnon et al, J. Biol. Chem., 261 (1986) 2548-2552). In addition, HDL may serve as a reservoir in the circulation for apoproteins necessary for the rapid metabolism of triglyceride-rich lipoproteins (Grow and Fried, J. Biol. Chem., 253 (1978) 1834-1841; Lagocki and Scanu, J. Biol. Chem., 255 (1980) 3701-3706; Schaefer et al, J. Lipid Res., 23 (1982) 1259-1273). Accordingly, agents which increase HDL cholesterol concentrations are useful as anti-atherosclerotic agents, particularly in the treatment of dyslipoproteinemias and coronary heart disease.
U.S. Pat. No. 5,137,904 discloses a group of thiohydantoin derivatives of the formula ##STR2## which Z is alkyl, phenylalkyl, phenyl or substituted phenyl, where the substituent is a halogen, alkyl, alkoxy or halogenated alkyl group; X is phenyl, halophenyl, alkyl, alkenyl, or alkynyl; and Y is S or O. These compounds inhibit collagen-induced and ADP-induced platelet aggregation.
EP 0584694 and WO 93/18057 disclose a group of imidazolidin-3-yl benzoyl or alkanoyl amino acid derivatives as inhibitors of cell-cell adhesion for use in inhibition of thrombocyte aggregation, metastasis and osteoclast formation. Chronic administration for prevention of arteriosclerosis and thrombosis is disclosed. ##STR3## in which Y=--(CH.sub.2).sub.n --CO-- or --Ph--CO--.
JP 04,297,461 discloses a group of 2-thiohydantoin compounds of the following formula, said to be useful as anti-bacterial, anti-viral, anti-inflammatory and anti-rheumatic agents: ##STR4## where R.sup.1 is lower alkyl, lower alkenyl, phenyl(lower)alkyl or substituted phenyl with 1-3 groups chosen from lower alkyl, lower alkoxy, halogen, lower alkoxycarbonyl or hydroxy;
R.sup.2 is either hydrogen or alkanoyl; and
R.sup.3 is hydrogen, lower alkyl, phenyl, phenyl (lower) alkyl, or a lower alkylthio, lower alkyl group that can be substituted with one to three phenyl groups that have had a lower alkoxy group.
EP 0578516 discloses a group of 2-thiohydantoins, said to be useful anti-androgenic agents for treatment of various cancer, of the formula: ##STR5## where X is oxygen or sulfur;
Y is oxygen, sulfur or NH
R.sup.1 and R.sup.2 are cyano, nitro, halogen, trifluoromethyl, or a free or esterified carboxylic acid or salt;
R.sup.3 is hydrogen, alkyl, alkenyl, alkynyl, aryl or aryl-alkyl;
R.sup.4 and R.sup.5 are hydrogen, optionally substituted alkyl, or cycloalkyl.
U.S. Pat. No. 5,411,981 discloses compounds closely related to EP 0578516, supra, where R.sup.4 and R.sup.5 are both methyl.
U.S. Pat. No. 3,923,994 discloses a group of 3-aryl-2-thiohydantoin derivatives of the following formula, which have anti-arthritic activity: ##STR6## where R.sup.1 and R.sup.2 are hydrogen, chloro, bromo, fluoro or alkyl of 1-2 carbon atoms.
JP 73 87,030 discloses a group of 3-phenyl-2-thiohydantoin derivatives useful as herbicides.
U.S. Pat. No. 4,473,393 discloses a group of pesticidal thiohydantoin compositions.